Mysterious FRBs came from dwarf galaxy located three billion light years away

Ever since 2007 when the first fast radio burst (FRB) was detected, researchers have been baffled and while these signals are still being considered baffling, a team of scientists have managed to figure out source of a repeating burst discovered in 2012.

Back in 2012, a team of astronomers detected repeating FRBs and this gave them the opportunity to monitor the area of the sky from where these signals were coming in. Researchers used Very Large Array (VLA) in New Mexico and the Arecibo radio dish in Puerto Rico to monitor this area and eventually pinpointed the source of the signal – a dwarf galaxy locate more than three billion light years from Earth. The VLA last year detected a total of nine bursts over a period of a month, sufficient to locate it within a tenth of an arcsecond.

Larger European and American radio interferometer arrays pinpointed it to within one-hundredth of an arcsecond, within a region about 100 light years in diameter. Deep imaging of that region by the Gemini North Telescope in Hawaii turned up an optically faint dwarf galaxy that the VLA subsequently discovered also continuously emits low-level radio waves, typical of a galaxy with an active nucleus perhaps indicative of a central supermassive black hole.

The dwarf galaxy is said to have lower amounts of hydrogen and helium suggesting that the galaxy is old – middle-aged in cosmic terms. The origin of a fast radio burst in this type of dwarf galaxy suggests a connection to other energetic events that occur in similar dwarf galaxies, said Casey Law, an astronomer University of California, Berkeley in the US. Law said that such galaxies are associated with extremely bright exploding stars, called superluminous supernovae and long gamma ray bursts. Both these phenomena are hypothesised to be associated with massive, highly magnetic and rapidly rotating neutron stars called magnetars.

Neutron stars are dense, compact objects created in supernova explosions, seen mostly as pulsars, because they emit periodic radio pulses as they spin. “All these threads point to the idea that in this environment, something generates these magnetars,” Law said.

“It could be created by a superluminous supernova or a long gamma ray burst, and then later on, as it evolves and its rotation slows down a bit, it produces these fast radio bursts as well as continuous radio emission powered by that spindown,” he said.

“Finding the host galaxy of this FRB, and its distance, is a big step forward, but we still have much more to do before we fully understand what these things are,” said team leader Shami Chatterjee of Cornell University. The research was published in the journal Nature and the Astrophysical Journal Letters.